I wonder what video card and kernel version are you using? If you are using an nvidia card then don't bother with the kernel's agpgart support as the nvidia driver has its own AGP routine. AGP supports the usage of main memory for the video chipset's engine. I believe that the maximum amount of RAM that can be allocated is referred to as the aperture size. This is an option that is typically set in your PC's BIOS, so try going into your BIOS setup and looking for that option. Perhaps you have it set to 256MB, try changing it to 64MB. Also, try updating your BIOS too (if you know the exact make and model of your motherboard).

Note that the kernel help for agpgart says this:

Quote:

If you need more texture memory than you can get with the AGP GART (theoretically up to 256 MB, but in practice usually 64 or 128MB due to kernel allocation issues) ....